You know everything started with Paywalling weapons. Look at PUBGM the monetization is Monstrous, many MOBA games like Vainglory has crazy monetization but you know what? They don't award the free players with an unfairness. Everything is fair in those games. The Monetization is purely on cosmetics.
Now in CODM the Perks on Paid weapons and Exclusive Paid Weapons are what making the community Angry.
I have never seen a perk like "Adding 3 bullets in Close Quarter Kill" being added to a free weapon, or sliding or jumping will give extra accuracy. Those perks are only on Pay2Get weapons.
Now exclusive paywall weapons, it all happy & good as long as that weapons didn't have any impacts but no, they added Pharo, Man-O-War, completely new weapons with new statistics behind a 0.01% drop chance and a scammy lucky draw. Later they added HBRa3, potentially the best weapon of the game.
Who knows? May be in coming days they will really add the new best weapon of the game behind a $200 Lucky draw.